Insecticidal composition



Patented Jan. 7, 1941 UNITED STATES PATENT OFFICE INSECTICIDAL COMPOSITION No Drawing. Application August 25, 1938, Serial No. 226,682

4 Claims.

This invention relates to insecticidal compositions and has for its principal object the provision of dusting compositions particularly adapted for the control of the celery thrip. This infesta- 5 tion on celery in certain sections of the country is increasingly becoming an economic problem,

particularly as the available insecticides give very poor control.

nicotine sulfate and organic thiocyanates, for example, have failed to give any satisfactory degree of control.

With the object of providing a satisfactory control for thrip on celery I have discovered a new and highly effective composition for this purpose consisting of a mixture of an organic thiocyanate such as dodecyl thiocyanate and tobacco dust dispersed in a suitable dusting powder such as bentonite. I am aware that organic thicyanates are well known insecticides and have been adsorbed on inert fillers and applied in the form of a dust. Such compositions, however, are relatively ineffective against thrip on celery. It has also been proposed broadly to employ organic thiocyanates in combination with other insecticides such as nicotine. But, so far as I am aware, it has not been suggested heretofore to absorb an organic thiocyanate on tobacco dust and disperse the product in an inert dusting powder.

As illustrative of my invention I may cite the following composition: Parts by weight Technical dodecyl thiocyanate 3 Ground tobacco stems 20 Bentonite '17 The technical dodecyl thiocyanate was first absorbed on the tobacco dust and the product then dispersed in the bentonite. The mixture was then screened and any lumps broken to a uniform pow- 40 der. The ground tobacco stems contained about one to one and twenty-five hundredths per cent nicotine.

A test plot of celery, approximately one-half acre, badly infested with thrip was dusted with the above composition. After an interval of fifteen to twenty minutes after dusting the celery plants were shaken and numerous thrips were found with little or no signs of life. Examination on the following day revealed only an occosional thrip left on the plants. Counts of the insects as nearly as could be made under the conditions indicated about ninety per cent killed.

A similar plot was simultaneously dusted with a mixture consisting of technical dodecyl thiocyanate and bentonite in proportions of three Such powerful contact poisons as pounds of the thiocyanate to ninety-seven pounds of bentonite and examination was made as described above. Not more than about forty per cent of the thrips were killed. Attempts to control thrip infestation on celery with aqueous 5 sprays of technical n-dodecyl thiocyanate and 1, nicotine sulfate were even less successful. Dusts consisting'of (1) pure ground tobacco stems, (2) nicotine sulfate adsorbed on bentonite in two,

three, and five per cent dusts, and (3) nicotine 1o sulfateabsorbed on pure ground tobacco stems to giveabout three per cent total nicotine content werelikewise ineffective.

It maylbe noted that the illustrative composition contains less than twenty-five hundredths 15 per cent nicotine. It is quite surprising, therefore, particularly in view of the almost completely negative results obtained with nicotine and nicotine sulfate even at many times this concentration, that this small amount of nicotine 20 would have such a pronounced effect. Without intending to limit my invention by any particular theory I believe that the effectiveness of my compositions is largely due to the absorptive properties of the tobacco dust. Unlike the usual in- 25 ert diluents such as bentonite, talc, and the like in which a liquid would be adsorbed rather than absorbed, the tobacco dust is a true absorbent for the organic thiocyanate. I believe that the fact that the organic thiocyanate is absorbed 30 rather than adsorbed accounts in a large measure for the effectiveness of my compositions. In any event the same advantageous results are not obtained without the tobacco dust irrespective of whether nicotine is present or not. 35

The compositions of my invention preferably contain technical n-dodecyl thiocyanate according to the Salzberg and Bousquet Patent 1,963,100 dated June 19, 1934. Other organic thiocyanates of the same type are described in the Salzberg 40 and Bousquet Patent 1,993,040 dated March 5, 1935, and may be used with similarly good results in preparing the compositions of my invention. It is to be understood, however, that in its broader aspects my invention is not limited to 45 the use of any particular organic thiocyanate, but that various other aliphatic, cyclo-aliphatic, aromatic, and similar organic thiocyanates may be employed with like effect. The higher aliphatic thiocyanates, however, such as disclosed in the 50 Bousquet and Salzberg patents, are particularly desirable in that the non-volatile character of these thiocyanates enhance the residual effect of the-dust. Moreover, compositions prepared with these thiocyanates may be applied to celery without injury even under the most severe weather conditions. For example, a small plot oi celery was treated once a week for four weeks with the composition given above by way of illustration. Even though the weather was severely hot with little or no rain, a condition inducive to injury following the application of insecticides, no detectable injury to the celery was observed.

It will be evident also that other inert dusting powders such as talc, kieselguhr, clays and the like may be used in lieu of the bentonite. The bentonite, however, is particularly desirable in that it prevents segregation and separation of the lighter particles of the tobacco dust and afiords better coverage and retention by reason of its colloidal or semi-colloidal nature.

The proportions given in the illustrative composition may, of course, be varied considerably without departing from the spirit of the invention. In general, however, the inert dusting powder should amount to about sixty per cent or more of the composition in order to obtain effective distribution of the thiocyanate-tobacco I dust mixture and to prevent such excessive local concentrations or the toxins as might cause injury to the plant. The thiocyanate content preferably should not be less than about three per cent and the tobacco dust should be sufllcient to adsorb the thiocyanate.

Other modifications consistent with the application of an insecticide as a dust may be made without departing from the spirit of my invention. Various types of conditioning agents may for example be included in the composition as desired to modify the storing, dusting, and retentive or adhesive properties of the composition. Likewise, various other insecticides and fungicides may be included whenever it is desired to effect simultaneous control of different types of pests. These and other variations may be made without departing from the spirit of the invention so long as an organic 'thiocyanate, preferably an allphatic thiocyanate containing at least eight carbon atoms such as dodecyl thiocyanate, is adsorbed on tobacco dust and dispersed in an inert dusting powder;

I claim:

1. As an insecticidal dusting composition an aggregate of uniformly distributed particles of tobacco dust and inert dusting powder in proportions such that a relatively small amount of the former is dispersed in and thruout the latter, and a liquid organic thiocyanate wholly absorbed and impregnating the particles of the tobacco dust whereby isolated regions of dimensions equivalent to the particle size of the tobacco dust and containing concentrations of the liquid organic thiocyanate substantially higher than the average concentration for the entire composition as a whole are distributed thruout the dusting composition.

2. As an insecticidal dusting composition an aggregate of uniformly distributed particles of ground tobacco stems having a nicotine content not substantially greater than 1.25% and bentonite in proportions such that a relatively small amount oi. the ground tobacco stems is dispersed in and thruout the latter, and dodecyl thiocyanate wholly absorbed and impregnating the particles of the tobacco dust whereby isolated regions 01' dimensions equivalent to the particle size of the finely ground tobacco stems and containing concentrations 01' dodecyl thiocyanate substantially higher than the average concentration for the composition as a whole are distributed thruout the dusting composition.

3. As an insecticidal dusting composition an aggregate of uniformly distributed particles of ground tobacco stems having a nicotine content not substantially greater than 1.25% and an inert dusting powder in proportions such that a relatively small amount of the former is dispersed in and thruout the latter, and a liquid organic thiocyanate wholly absorbed and impregnating the particles or the ground tobacco stems whereby isolated regions of dimensions equivalent to the particle size of the tobacco dust and containing concentrations of the liquid organic thiocyanate substantially higher than the average concentration tor-the entire composition as a whole are distributed thruout the dusting composition.

4. As an insecticidal dusting composition an aggregate o1 uniformly distributed particles of ground tobacco stems having a nicotine content not substantially greater than 1.25% and bentonite in proportions such that a relatively small amount of the ground tobacco stems is dispersed in and thruout the latter, and a liquid organic thiocyanate wholly absorbed and impregnating the particles of the tobacco dust whereby isolated regions 01' dimensions equivalent to the particle size of the finely grounded tobacco stems and containing concentrations of the thiocyanate substantially higher than the average concentration for the composition as a whole are distributed thruout the dusting composition.

LIONEL E. TISDALE. 

